Java –如何打印数组

╰+攻爆jí腚メ 2023-02-15 05:08 10阅读 0赞

在本文中，我们将向您展示几种打印Java数组的方法。

## 1. Arrays.toString ##

这是打印数组的最简单方法– `Arrays.toString` （自JDK 1.5起）

PrintArray.java

package com.mkyong.utils.print;
    
    import java.util.Arrays;
    
    public class PrintArray {
    
        public static void main(String[] args) {
    
    		// array
            String[] arrayStr = new String[]{"Java", "Node", "Python", "Ruby"};
            System.out.println(Arrays.toString(arrayStr));
            // Output : [Java, Node, Python, Ruby]
    
    		int[] arrayInt = {1, 3, 5, 7, 9};
            System.out.println(Arrays.toString(arrayInt));
            // Output : [1, 3, 5, 7, 9]
    
            // 2d array, need Arrays.deepToString
            String[][] deepArrayStr = new String[][]{
        {"mkyong1", "mkyong2"}, {"mkyong3", "mkyong4"}};
            System.out.println(Arrays.toString(deepArrayStr));
            // Output : [[Ljava.lang.String;@23fc625e, [Ljava.lang.String;@3f99bd52]
    
            System.out.println(Arrays.deepToString(deepArrayStr));
            // Output : [[mkyong1, mkyong2], [mkyong3, mkyong4]
    
            int[][] deepArrayInt = new int[][]{
        {1, 3, 5, 7, 9}, {2, 4, 6, 8, 10}};
            System.out.println(Arrays.toString(deepArrayInt));
            // Output : [[I@3a71f4dd, [I@7adf9f5f]
    
            System.out.println(Arrays.deepToString(deepArrayInt));
            // Output : [[1, 3, 5, 7, 9], [2, 4, 6, 8, 10]]
    
        }
    
    }

输出量

[Java, Node, Python, Ruby]
    [1, 3, 5, 7, 9]
    [[Ljava.lang.String;@23fc625e, [Ljava.lang.String;@3f99bd52]
    [[mkyong1, mkyong2], [mkyong3, mkyong4]]
    [[I@3a71f4dd, [I@7adf9f5f]
    [[1, 3, 5, 7, 9], [2, 4, 6, 8, 10]]

## 2. JDK 8流 ##

在JDK 8中，我们可以将其转换为[Stream][]并进行打印。

PrintArray.java

package com.mkyong.utils.print;
    
    import java.util.Arrays;
    
    public class PrintArray {
    
        public static void main(String[] args) {
    
            // array
            String[] arrayStr = new String[]{"Java", "Node", "Python", "Ruby"};
            Arrays.stream(arrayStr).forEach(System.out::println);
    
            int[] arrayInt = {1, 3, 5, 7, 9};
            Arrays.stream(arrayInt).forEach(System.out::println);
    
            //2d array
            String[][] deepArrayStr = new String[][]{
        {"mkyong1", "mkyong2"}, {"mkyong3", "mkyong4"}};
            Arrays.stream(deepArrayStr).flatMap(x -> Arrays.stream(x)).forEach(System.out::println);
    
            int[][] deepArrayInt = new int[][]{
        {1, 3, 5, 7, 9}, {2, 4, 6, 8, 10}};
            Arrays.stream(deepArrayInt).flatMapToInt(x -> Arrays.stream(x)).forEach(System.out::println);
    
        }
    
    }

输出量

Java
    Node
    Python
    Ruby
    1
    3
    5
    7
    9
    mkyong1
    mkyong2
    mkyong3
    mkyong4
    1
    3
    5
    7
    9
    2
    4
    6
    8
    10

## 3.杰森 ##

这是我最喜欢的方法，请使用[Jackson2][]库以JSON格式的字符串打印任何内容。

PrintUtils.java

package com.mkyong.utils.print;
    
    import com.fasterxml.jackson.core.JsonProcessingException;
    import com.fasterxml.jackson.databind.ObjectMapper;
    
    public class PrintUtils {
    
        private static final ObjectMapper om = new ObjectMapper();
    
    	public static void print(Object object) {
    		String result;
    		try {
    			result = om.writerWithDefaultPrettyPrinter().writeValueAsString(object);
                System.out.println(result);
            } catch (JsonProcessingException e) {
    			e.printStackTrace();
    		}
    	}
    	
    }

PrintArray.java

package com.mkyong.utils.print;
    
    public class PrintArray {
    
        public static void main(String[] args) {
    
    		//array
            String[] arrayStr = new String[]{"Java", "Node", "Python", "Ruby"};
            PrintUtils.print(arrayStr);
    
            int[] arrayInt = {1, 3, 5, 7, 9};
            PrintUtils.print(arrayInt);
    
    		//2d array
            String[][] deepArrayStr = new String[][]{
        {"mkyong1", "mkyong2"}, {"mkyong3", "mkyong4"}};
            PrintUtils.print(deepArrayStr);
    
            int[][] deepArrayInt = new int[][]{
        {1, 3, 5, 7, 9}, {2, 4, 6, 8, 10}};
            PrintUtils.print(deepArrayInt);
    
        }
    
    }

输出量

[ "Java", "Node", "Python", "Ruby" ]
    [ 1, 3, 5, 7, 9 ]
    [ [ "mkyong1", "mkyong2" ], [ "mkyong3", "mkyong4" ] ]
    [ [ 1, 3, 5, 7, 9 ], [ 2, 4, 6, 8, 10 ] ]

## 参考文献 ##

1.  [Steam Javasoc][Stream]
2.  [数组JavaDoc][JavaDoc]
3.  [杰克逊2将Java对象转换为JSON][2_Java_JSON]
4.  [杰克逊2官方网站][Jackson2]

标签： [数组][Link 1] [Java][]

> 翻译自: [https://mkyong.com/java/java-how-to-print-an-array/][https_mkyong.com_java_java-how-to-print-an-array]

[Stream]: https://docs.oracle.com/javase/8/docs/api/java/util/stream/Stream.html
[Jackson2]: http://wiki.fasterxml.com/JacksonRelease20
[JavaDoc]: https://docs.oracle.com/javase/8/docs/api/java/util/Arrays.htm
[2_Java_JSON]: http://www.mkyong.com/java/jackson-2-convert-java-object-to-from-json/
[Link 1]: https://mkyong.com/tag/array/
[Java]: https://mkyong.com/tag/java/
[https_mkyong.com_java_java-how-to-print-an-array]: https://mkyong.com/java/java-how-to-print-an-array/